Changes in this update:
**Enhancements**
* `AuthDelegate` and `AuthServer.py` have been replaced by `CBLAUthDelegate`, which provides a more straightforward path to authorization.
* Added a new configuration property called [`cblAuthDelegate`](https://github.com/alexa/avs-device-sdk/blob/master/Integration/AlexaClientSDKConfig.json#L2). This object specifies parameters for `CBLAuthDelegate`.
* Added a new configuration property called [`miscDatabase`](https://github.com/alexa/avs-device-sdk/blob/master/Integration/AlexaClientSDKConfig.json#L34), which is a generic key/value database to be used by various components.
* Added a new configuration property called [`dcfDelegate`](https://github.com/alexa/avs-device-sdk/blob/master/Integration/AlexaClientSDKConfig.json#L17) This object specifies parameters for `DCFDelegate`. Within this object, values were added for the 'endpoint' and `overridenDcfPublishMessageBody`. 'endpoint' is the endpoint to connect to in order to send device capabilities. `overridenDcfPublishMessageBody`is the message that will get sent out to the Capabilities API. Note: values within the `dcfDelegate` object will only work in `DEBUG` builds.
* Added a new configuration property called [`deviceInfo`](https://github.com/alexa/avs-device-sdk/blob/master/Integration/AlexaClientSDKConfig.json#L9) which specifies device-identifying information for use by the Device Capability Framework (DCF), and for authorization (CBLAuthDelegate).
* Updated the Directive Sequencer to support wildcard directive handlers. This allows a handler for a given AVS interface to register at the namespace level, rather than specifying the names of all directives within that namespace.
* Updated the Raspberry Pi installation script to include `alsasink` in the configuration file.
* Added `audioSink` as a configuration option. This allows users to override the audio sink element used in `Gstreamer`.
* Added an interface for monitoring internet connection status: `InternetConnectionMonitorInterface.h`.
* The Alexa Communications Library (ACL) is no longer required to wait until authorization has succeeded before attempting to connect to AVS. Instead, `HTTP2Transport` handles waiting for authorization to complete.
* Added the Device Capabilities Framework (DCF) delegate. Device capabilities can now be sent for each capability interface using DCF publish messages.
* The sample app has been updated to send DCF publish messages, which will automatically occur when the sample app starts. Note: a DCF publish message must be successfully sent in order for communication with AVS to occur.
* The SDK now supports HTTP PUT messages.
* Added support for opt-arg style arguments and multiple configuration files. Now, the sample app can be invoked by either of these commands: `SampleApp <configfile> <debuglevel>` OR `SampleApp -C file1 -C file2 ... -L loglevel`.
**Bug Fixes**
* Issues [447](https://github.com/alexa/avs-device-sdk/issues/447) and [553](https://github.com/alexa/avs-device-sdk/issues/553) Fixed the `AttachmentRenderSource`'s handling of `BLOCKING` `AttachmentReaders`.
* Updated the `Logger` implementation to be more resilient to `nullptr` string inputs.
* Fixed a `TimeUtils` utility-related compile issue.
* Fixed a bug in which alerts failed to activate if the system was restarted without network connection.
* Fixed Android 64-bit build failure issue.
**Known Issues**
* The `ACL` may encounter issues if audio attachments are received but not consumed.
* `SpeechSynthesizerState` currently uses `GAINING_FOCUS` and `LOSING_FOCUS` as a workaround for handling intermediate state. These states may be removed in a future release.
* Some ERROR messages may be printed during start-up event if initialization proceeds normally and successfully.
* If an unrecoverable authorization error or an unrecoverable DCF error is encountered, the sample app may crash on shutdown.
* If a non-CBL `clientId` is included in the `deviceInfo` section of `AlexaClientSDKConfig.json`, the error will be reported as an unrecoverable authorization error, rather than a more specific error.
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